Apparatus for grinding cylindrical workpieces

ABSTRACT

An apparatus for continuously grinding a multiplicity of cylindrical workpieces required to be concentrically ground with reference to their axes. The apparatus comprises an upper elastic feed belt adapted to push downwardly and roll the cylindrical workpieces around their axes on a rolling table and a lower grinding belt adapted to be moved at a high rate of speed so as to grind the rolling surfaces of said cylindrical workpieces.

Inventors: Shinichi Miyazawa, Kawasaki;

Hidehiko Takeyama; Kaneyoshi Miyasaka, both of Tokyo, all of Japan Assignee: Agency of Industrial Science &

Technology, Tokyo, Japan Filed: Apr. 1, 1974 Appl. No.: 456,441

Foreign Application Priority Data June 18, 1973 Japan 48-68477 References Cited UNITED STATES PATENTS Otten 5l/l44 X United States Patent [191 [111 3,909,986 Miyazawa et al. Oct. 7, 1975 [5 APPARATUS FOR GRINDING 2,579,604 12 1951 Niederer 51/138 CYLINDRICAL WQRKPIECES 2,936,555 5/1960 Junge 51/140 X FOREIGN PATENTS OR APPLICATIONS 968,437 2/1958 Germany 51/138 Primary ExaminerAl Lawrence Smith Assistant Examiner-Nicholas P. Godici Attorney, Agent, or FirmOblon, Fisher, Spivak, McClelland & Maier [57] ABSTRACT An apparatus for continuously grinding a multiplicity of cylindrical workpieces required to be concentrically ground with reference to their axes. The apparatus comprises an upper elastic feed belt adapted to push downwardly and roll the cylindrical workpieces around their axes on a rolling table and a lower grinding belt adapted to be moved at a high rate of speed so as to grind the rolling surfaces of said cylindrical workpieces.

3 Claims, 2 Drawing Figures APPARATUS FOR GRINDING CYLINDRICAI. WORKPIECES BACKGROUND OF THE INVENTION This invention relates to a cylindrical grinding appa- ItItUS.

Generally in the operation of grinding a cylindrical workpiece, concentrically with reference to the axis thereof. the workpiece is axially fastened by means of a chuck or center. Therefore, considerable time and labor are required in fastening the workpiece to and removing the finished cylinder from the grinding machine. As operation must be interrupted during this fastening and removal work, it is impossible to improve the operating efficiency of the machine.

An object of this invention is to provide a cylindrical grinding apparatus which is capable of continuously and efficiently grinding cylindrical workpieces concentrically with reference to their respective axes without axially fastening the workpieces by means of a chuck or center.

SUMMARY OF THE INVENTION To accomplish the object described above, the cylindrical grinding apparatus according to this invention has a lower platen having an endless grinding belt running at a high rate of speed thereon and an upper platen having a resilient feed belt running thereunder disposed opposite the'lower platen. Along each side of the lower platen, there is disposed a rolling table for imparting a rolling motion to the shafts of the cylindrical workpieces. As cylindrical workpieces are fed into the opening between the two platens, the frictional force of the feed belt amply predominates over the grinding force so that the workpieces are simultaneously rotated and ground between the two platens. Since the workpieces are not axially fastened by means of a chuck or center, a large number of workpieces can continuously be ground. Since the shafts of the workpieces are made to roll on the rolling tables, the workpieces can be concentrically ground with reference to their respective axes to a prescribed size in the same way as when the workpieces axially fastened by means of a chuck are acted upon by a cutting tool.

Other objects and other characteristics of the present invention will become apparent from the description of this invention to be given more specifically herein below with reference to the attached drawing.

BRIEF EXPLANATION OF THE DRAWING FIG. 1 is a side elevational view illustrating one preferred embodiment of the cylindrical grinding apparatus according to this invention.

FIG. 2 is a cross-sectional view taken along the line II-II of the apparatus of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION Referring to the drawing, an endless grinding belt 1 is passed around a driving pulley 6, an idle pulley 7 and a tension pulley 8 which are rotated by a suitable driving means (not illustrated). The rotation of the driving means causes this grinding belt I to travel at a high rate of speed on a platen 2 in the direction of the arrow mark. An endless feed belt 3 adapted to convey workpieces is passed around a driving pulley 9 and an idle pulley 10. A platen 4 is disposed opposite the platen 2 and adapted to keep the feed belt 3 in position. The feed belt 3 is driven to rotate oppositely to grinding belt 1 so that part of the feed belt 3 and the part of the grinding belt I facing each other travel in the same direction. A rolling table 5 is disposed on either side of the platen 2. These rolling tables 5 receive and support shafts 12 which protrude from either end of workpieces 1 I. The feed belt 3 maintains itself in a depressed state so as to keep contact with the surface of workpieces 11. The two opposed rolling tables are separated from each other by a distance equalling the width of the cylindrical workpieces to be handled. Alternatively, projections 5' may be provided as illustrated in FIG. 2, so that the workpieces will be prevented from swerving with respect to the direction of thrust while being ground. The feed belt 3 is made of a substance such as, for example, polyurethane rubber which abounds in resilience and friction. The frictional force produced by the pressed contact between the surface of the workpieces 11 and that of the feed belt 3 overcomes the frictional force exerted by the grinding belt 1 upon the workpieces II, with the result that the workpieces 11 are rolled in the direction of the arrow mark.

The platen 2 comprises an anterior part 2a inclined on the receiving side of the apparatus with reference to the rolling tables so as to provide gradually increased grinding for unground workpieces having a large diameter and a posterior part 217 disposed parallel to the rolling tables so as to finish the workpieces 11 to the prescribed size. Similarly the platen 4 comprises an anterior part 4a inclined on the receiving side of the apparatus so as to facilitate reception of unground workpieces having a large diameter and a posterior part 412 disposed parallel to the corresponding parallel part 21) of the platen 2. Simultaneous incorporation of the two inclined parts 2a and 4a, one in each platen, is not an essential requirement. Use of one inclined part in either of the two platens suffices for the purpose.

On the outer side of each rolling table 5, an endless chain 13 having regularly spaced bearing boxes 14 attached thereto travels in parallel relation to the grinding belt I. The chain 13 is passed around a pair of opposed sprockets 15. The rotation of the sprockets keeps the chain 13 in motion. The bearing boxes 14 are so constructed that their bottoms do not rise above the upper surface of the rolling tables 5. Thus, the workpieces pass, while rolling between the platens 2 and 4, with the shafts 12 at both ends thereof riding over the rolling tables and with the tips of these shafts inserted in the bearing boxes.

In the cylindrical grinding apparatus of this invention which has a construction as described above, when the workpieces 11 are sequentially fed thereto on the supply side, the tips of the shafts of the workpieces are received into the bearing boxes 14 and the shafts l2 themselves are mounted on the rolling tables 5. With the workpieces held in this state, the feed belt 3 imparts a rolling motion to the workpieces and the motion of the chain carries them to the inclined parts 2a and 4a of the platens 2 and 4. After the workpieces 11 have been conveyed to the inclined parts 2a and 4a of the platens 2 and 4, the grinding belt 1 which travels at a high rate of speed in the direction opposite that of the rotation of the workpieces begins to gradually grind the surface of the workpieces. While the grinding work is in progress, the workpieces are prevented from skewing by the rolling tables 5 or the projections 5 thereon.

The speed of the grinding belt and that of the feed belt are adjusted in the range of from 1200 to 1800 m/min and in the range of from 0.5 to l m/min, respectively, although both speeds are variable with such factors as the shape and material of the workpieces, the amount of grinding, the length of the platens, the friction coefficient of the feed belt and the traveling speed of the workpieces (traveling speed of the chains). Since the speeds of the two belts differ greatly as described above, the directions in which the two belts are caused to travel along the opening need not necessarily be opposite. The grinding effect produced by the present apparatus is substantially the same even when they are caused to travel in the same direction along the open- The distance between the parallel parts of the two platens and the height of the rolling tables are selected with due consideration paid to the thickness of the grinding belt and that of the feed belt, so that the workpieces will be ground in the prescribed amount.

As described above, the workpieces are rolled on the rolling tables by the feed belt, with the rate of their conveyance controlled by means of the bearing boxes. The workpieces, while in transit, are ground to a prescribed size throughout their entire circumferences, with the axial direction of the workpieces maintained perpendicular to the direction in which the belts travel.

As is clear from the foregoing explanation, the cylindrical grinding apparatus of this invention permits workpieces to be received, ground and discharged continuously without requiring them to be fastened to the table of a grinding machines. Unlike the conventional grinding means which involves as many interruptions of operation as the number of workpieces being handled, the present apparatus permits a multiplicity of workpieces to be simultaneously ground, making it possible to improve the operating efficiency of the apparatus to a great extent. Further, since the pressure with which the grinding belt is held in contact with the workpieces is made uniform so as to provide the required degree of grinding under a fixed pressure, this apparatus enables workpieces to be ground accurately to a fixed size despite possible dimensional variation involved in the previous stage of machining.

What is claimed is:

1. An apparatus for grinding cylindrical workpieces having axially extending shafts on the opposites ends thereof, comprising in combination:

an upper platen;

a lower platen disposed opposite said upper platen;

a grinding belt arranged to run at a high speed over said lower platen;

a feed belt arranged to travel under said upper platen, said feed belt producing on said workpieces to be ground a frictional force greater than the force which said grinding belt exerts thereon;

a pair of rolling tables disposed respectively along each side of said lower platen to receive said shafts of said workpieces; and

means for conveying said workpieces through the opening between said grinding belt and said feed belt,

whereby the feed belt causes the shafts of a multiplicity of workpieces to be pressed against and rolled on said rolling tables while the workpieces are being ground to a fixed size by said grinding belt.

2. An apparatus according to claim 1, wherein the said opposed platens each comprises an anterior part inclined divergently toward the workpiece receiving side and a posterior parallel part.

3. An apparatus according to claim 1, wherein the rate of speed of the grinding belt is much greater than that of the feed belt. 

1. An apparatus for grinding cylindrical workpieces having axially extending shafts on the opposites ends thereof, comprising in combination: an upper platen; a lower platen disposed opposite said upper platen; a grinding belt arranged to run at a high speed over said lower platen; a feed belt arranged to travel under said upper platen, said feed belt producing on said workpieces to be ground a frictional force greater than the force which said grinding belt exerts thereon; a pair of rolling tables disposed respectively along each side of said lower platen to receive said shafts of said workpieces; and means for conveying said workpieces through the opening between said grinding belt and said feed belt, whereby the feed belt causes the shafts of a multiplicity of workpieces to be pressed against and rolled on said rolling tables while the workpieces are being ground to a fixed size by said grinding belt.
 2. An apparatus according to claim 1, wherein the said opposed platens each comprises an anterior part inclined divergently toward the workpiece receiving side and a posterior parallel part.
 3. An apparatus according to claim 1, wherein the rate of speed of the grinding belt is much greater than that of the feed belt. 